Pinhole grinder mandrel



Feb. 5, 1935. J. sU-NNEN PINHOLE GRINDER MANDREL Filed Feb. 6, 1935 2 Sheets-Sheet 1 ix 1 N U /5 m x 0 J @Tram/5K Feb. 5,1935. J. sUNNEN PINHOLE GRINDER MANDREL 2 Sheets-Sheet 2 Filed Feb. 6, 1935 Patented Feb. s, 193sV y 1,989,831

UNITED STATES PATENT OFFICE PINnoLE GmNnEn MANDREL JosephvSunnen, Kirkwood, Mo.

' Application February 6, 1933, Serial No. 655,392

' 9 emma. (ci. 51-1s4.3)

My invention has relation to improvements in the mandrel and said device; Fig. 3 is a plan view machines for grinding small holes, such as the of the mandrel together with the connecting link wrist pin holes of engine pistons, and itconsists of the mechanism for effecting radial adjustment in the novel features of construction more fully of the abrasive element; Fig. 4 is a vertical longi- 5 set forth in the specification and pointed out in tudinal section through a part of the mandrel 0 the daims, taken on the zig-zag line 4-4 of Fig. 3; Fig. 5

The present invention is directed specifically is a. bottom plan of the mandrel; Figs. 6, 7 and to the holder or mandrel for the abrasive elementV 8 are vertical cross-sectional views taken on the and is anA improvement over the mandrel delines 6 6, '7 7 and 8 8 respectively of Fig. 3;

10 scribed and claimed in my co-pending applica- Fig. 9 is a perspective view of the inner end of 10 tion, Serial No. 578,923', filed December 4, 1931. the abrasive element showing the hook whereby` Grinding operations are performed by means said element engages the body of the mandrel; of my improved grinder in the same manner as Fig. 10 is a vertical longitudinal section through they are performed by the grinder of the apthe mandrel taken on the line 10--10 of Fig. 3i

plication jus"I referred to. That is to say, the Fig. 11 is an enlarged middle longitudinal section mandrel is rigid1y connected to a rotatable shaft of the inner enlarged end of the mandrel together and the piston pin holes are ground by moving withthe connections to the driving mechanism; the piston backand forth over'the mandrel so and Fig. 12 is a horizontal cross-section taken A that the abrasive element will traverse said holes through the inner end of the mandrel and couas it is revolved. It is quite apparent that as the pling nut on the plane indicated by the line 20 v operator moves the piston back and forth to effect 12-12 0f Fig. 11.

the grinding of the holes he will exert some pres- Referring to the drawings, 1 represents my msure on the mandrel (as the piston is allowed to proved mandrel terminating at its inner end in iioat) and of course impose strains therein so' spaced flanges 2, 2', both of which' are received that means must be embodiedinthe mandrel and within a socket 3 of a coupling nut 4 having 25 also in the elongated abrasive element to prevent threads 4 formed in the inner endthereof wherepermanent distortion of the mandrel or breaking by the coupling nut is secured on the threaded of the stone. It is one of the objects of the present extremity 5 of a driving spindle 5 mounted in a invention to provide such means. In the present bea-ring 6 which forms a part of the actuating invention, as in that heretofore referred to, the device for the mandrel. An annular ange 7 is 30 v abrasive element is adjustable radially with reformed within the nut 4 against which the end of spe'ctA to the mandrel in order thatnit may be spindle 5 abuts when the nut 4.is tightly screwed v adapted forrgrinding'f'holes of different'sizes, and thereon. A disk 8 is secured within the'nut 4 in it is one of the objects of the present invention abutting relation with the flange 7 (preferably by 85 to provide a means of effecting such adjustment being driven into said nut) and said disk has a 35 that will give a greater range of adjustment than slot a formed inwardly from its periphery to apthat 'heretofore obtained proximately the center thereof through which is It is also an object of the invention to embody driven a key 8. One end of the key 8' projects in the mandrel means for securing the abrasive into the socket 3, and the other end of said key 40 element therein in a manner that said 'element fits tightly in a recess r formed in the flange 'I 40 may be easily and quickly removed when desired. (Figs. 11 and 12) It will be observed by referring A further object is to provide an abrasive eleto Fig. 11 that when the mandrel is secured withment that although rigidly held in the mandrel in the nut 4 the outer end of key 8' enters the possesses flexibility so that it is capable of acpart 10 of a longitudinally disposed slot 10 excommodating itself to the slightvflexing action tending throughout the full length of the man- 45 that may take place in the mandrel during operdrel except at its outer extremity where the slot ation. These and other advantages will be better is closed by wall 11, and since the inner end of apparent from a detailed description of the inthe key ts in the recess 1' of flange 'I the mandrel 'vention in connection with the accompanying is securely connected to said nut 4, the key 8' servdrawings, in which: ing as a driving lug therefor. In order to prevent 50 j Figure 1 is a side elevation of my improved pin the mandrel from moving longitudinally out of Ahole grinder mandrel connected to a suitable acthe socket 3 of nut 4 a set-screw 9 is passed tuating device therefor; Fig. 2 is a vertical lonthrough the nut and caused to firmly engage with gitudinal section through the mandrel and acthe mandrel between the flanges 2 and 2'.

tuating device showing the connections between There are three spaced shallow bosses 12, 12, 12 55 .formed on the bottom of the slot 1e and a rib 13 is formedv on one side wall o f the s'i-:Jt adjacent to the innermost boss 12 for a purpose presently to appear. The slot 10 is adapted to' receive an abrasive element E comprising two stick members 14, 14 having their adjacent ends loosely coupled by means of a tongue 15 projecting from the end of one member and a recess lai-formed in the end of the other member together with a hinge pin 17 passed through said tongue and the end of the member 14 adjacent thereto, as shown 'in Fig. 2. Abrasive stones v18, 18 of carborundul'n, or. equivalent material, are securely xed to the upper surfaces of the sticks i4; 14 by `cement or otherwise so as in eect constitute an integral part of the sticks. The free end of inner stick 14 is provided with an upwardly tapered recess 19 in one side for the purpose of receiving the rib 13 projecting from the side of slot 10 whereby the' abrasive element E is securely held in the mandrel at its inner end. The free end of the outer stick 14 is notched at 20 so as to provide a hook for y engaging the downwardlybent extremity 121' of link 2l which serves as an anchor, for the abrasive element E. Ihe outer end 22 of the anchor iink 21 is perforated so that it may be slidably mounted 0n a pin 23 secured into the end wall 11 of the mandrel 1 and projecting into the slot l0. "A coiled spring 24 is mounted on the pin 23 between the inner head 25thereof andthe downwardly bent end 22 of .the link 21 so as to continually urge said link 21 outwardly and thereby exert an outward pull on the abrasive element E, thus holding said abrasive element rinly in the mandrel.

The link 20 is provided with an elongated opening 26 whereby it may be engaged by a suitable tool for disengaging the link from the abrasive element when it is necessary to remove said element from the mandrel.

It will be observed (Figs. 2, 3 and 4) that each stick 14 has wedge-shaped bosses 27, 27' formed on the side opposite to that containing the notch 19 and the bosses being adjacent to the ends of each stick. 'Ihe bottom edges e, e' of the bosses are inclined downwardly toward the outereendof the mandrel (when the abrasive stick is inserted therein), and theedges e', e'of the adjacent bosses 27227 together form a continuous inclined ssurface. The presence of the bosses 27, 27' obviously resultsin' the formation of a clear space between the sides of the sticks 14, 14 and the adjacent side ef the recess 10. A wedge-bar'28 is positioned in this space S with its' bottom plane edge 29 adapted to ride on the bosses l2 and its wedge-V formations 30, 31, '32 beneath the wedge-bosses 27 and 27 of each stick 14 (Fig. 10) It is quite apparent that moving the wedge-bar 23 outwardly (that is, toward the free end of the inandr'el)A would cause the wedges 30 to slide under the wedge-bosses 27A and 27'v to raise them and, of course, the sticks 14, 14 so that the abrasive ele' ment is adjusted radially eutwardly from the mandrel. There is, of course, suiiicient flexibility in the connectionbetween the 4hook 21 and adjacent stick 14 to permit this sticky to movefreely under-the in'uence of the' wedge-bar 28. The inner end of wedge-bar 28 is provided with a hook 33 to engage a notch 34 formed on thev free end of a link 35 whichferms the connection between the wedge-bar 28 and adjusting screw 36 operating through a threaded opening 37 ln a socket 38 on the inner end of the link 35. vAs in my pending application, Serial No. 578,923, the link :35 is caused to move lback and forth by turning a inner end of which is ex-ibiy connected at 41 the screw 36.

The mandrel-1 has longitudinally extending ribs 42` and 43 formed on its periphery in spaced relation, the length of said ribs being co-extensive with that of the abrasive element E, and the rib 42 being circumferentially closer to the stone 18 than the rib 43. It will be observed that the ribs 42, 43 are slightly narrower for a short distance inwardly from their outer extremities, as shown at 42', 43'. The purpose of the ribs is to serve as guide elements for the abrasive element E as the mandrel is rotated inl a piston pinj holefor the.

irrespective of the position to'which the abrasive l stone and the guides will be somewhat equalized.`

In the operation of the grinding device the opelenient is adjusted as the three point contact s erator positions the piston on the mandrel so that the mandrel traverses both the piston pin holes, and while the mandrel rotates the operator manually moves the piston back and 'forth over practically the entire extent of the abrasive element E. During -t-iiis operation. it is apparent that some pressure will be caused to bear on the mandrel and cause it to bend slightly because of its small diameter in comparisonwith its longi- 1 tudinal extent. If the abrasive element E were made in one piece the pressure exerted on the mandrel would cause' it to fracture since the.

abrasive stenes possess little or no flexibility in themselves. It is to prevent fracturing of the abrasive stones that I form the abrasive element E ef two members which are ilexibly conneeted, as above described. The mandrel 1 being made of a suitable metal possesses inherent iiexibility the"=wedgebar 428. being greatly reduced in width between the wedge-formations 31 and 32, is also sufliciently flexible tobend with'the man-y drel should suillcient vpressure be applied thereto byA the operator during his work. Should the operator desire to remove the abrasive element E at any time heysimplyfdisengages the link 21 fromy the hook 20 whereuponthe abrasive element may" be lifted out of the recess 1G.

' The coupling mechanism. essentially the nut 4 and link 35, make it l"possible for themandrel' to be connected to the driving mechanism easily and quickly. For instance, the operator merely inserts the ilanges 2, 2' in the socket'3 of nut 4 (first sliding the wedge-bar 28 until the hook 33 extends beyond the flange 2' and making sure that the link 35 is adjusted outwardly far enough foi-iis notch 34 to register Iwith said hook sa), after which the mandrel is rotated (as shown by the arrows in Fig. 12) so that said notch and hook 33'wiil come into engagement (asshown in Fig. 3). The operator now pushes the mandrel inwardly until the Lilange 2' abuts against4 thev disk 8,v at which time the key 8' will have entered slot 10 to'eouple themandrel to the nut 4 and, of course, to the driving spindle 5. vThe slet 10' is sumciently wide to also receive within it ,the

link 35, as shown, as this link and also adjusting screw 36 rotate in unison with the mandrel during the grinding operations.

Having described my invention, I claim:

l. In a grinding machine, a mandrel having a longitudinally disposed recess, an abrasive element in said recess, and means for holding the abrasive element in place, said abrasive element com' prising a plurality of connected members.

A2. .In a grinding machine, a mandrel having a longitudinally ldisposed recess, a jointed abrasive element in said recess, and means for holding the abrasive element in place.

3. In agrinding machine, a mandrel having a longitudinally disposed recess, a pair of longitudinally extending guide elements on the periphery of the mandrel circumferentially spaced from each' other and from said recess, and a plurality of abrasive members disposed end to end in said recess and collectively co-extensive with the guide elements.

'4. In a grinding machine. a mandrel having a longitudinally disposed recess, a pair of longitudinally extending guide elements fixed on the periphery ofr the mandrel circumferentially spaced from each other and from said recess, a plurality of abrasive members disposed end to end in said recess and collectively coextensive with the guide elements, and means for simultaneously adjusting said abrasive members radially of the mandrel.

5. Ina grinding machine, a mandrel having a longitudinally disposed recess, a ilexible abrasive element in said recess, said element having a plurality of Wedge-bosses in spaced relation, a Wedgebar disposed in said recess having a plurality of wedge-surfaces to engage with the wedge-bosses for moving the abrasive element radially of the mandrel with a longitudinal movement of the wedge-bar, and means for holding the abrasive element in place, said means exerting tension on the abrasive element in the same direction that the wedge-bar is movable to eiect outward adjustment thereof.

6. In a grinding machine, a mandrel having a longitudinally disposed recess, a flexible abrasive element in said recess, said element having a plurality of wedge-bosses in spaced `relation, a wedge-bar disposed in said recess between the abrasive element and side of said recess, said wedge-bar having a plurality of wedge-surfaces torengage with the wedge-bosses for moving th#` abrasive element radially of the mandrel with a longitudinal movement of the wedge-bar, and means for holding the abrasive element in place.

7. In a grinding machine, a mandrel, driving lmechanism therefor, said mandrel having a longitudinally disposed slot, a grinding., element mounted in said slot, a member slidable longitudinally to eiect changes in the position of the grinding member, means for coupling the man-l drel to said driving mechanism, means associated with the driving mechanism for actuating said slidable member, and interlocking devices on the slidable member and actuating means for said member, said interlocking devices being arranged to interlock with a relative rotation thereof.

8. In a grinding machine, a mandrel, driving mechanism therefor, a grinding element mounted in said mandrel, said driving mechanism including a driving spindle terminating in a socket at one end, a driving lug in said socket, said mandrel having a slotted flange at one end adapted to enter said socket, said lug entering the slot in the mandrel flange to couple the mandrel to the driving spindle, and means associated with the driving means for effecting changes in the position of the grinding element, said last named means being disposed in the slotted flange.

9. In a grinding machine, a mandrel having a longitudinally disposed recess, a driving mechanism for said mandrel, a grinding .element and a longitudinally. slidable member mounted in said slot, means for coupling the mandrel to said driv- .ing mechanism, and means associated with the coupling means for actuating the slidable member, said coupling means including a drive lug, said actuating means including a connecting link for engagement with the slidable member, means `for maintaining the connecting link in radial 

